Variable output pumping means



Dec. 8, 1964 c. A. CLARK VARIABLE OUTPUT PUMPING MEANS 2 Sheets-Sheet 1 Filed July 29, 1963 INVENTOR 6/04/04? 4. 6/67/14 C. A. CLARK VARIABLE OUTPUT PUMPING MEANS Dec. 8, 1964 2 Sheets-Sheet 2 Filed July 29, 1963 INVENTOR C/auc/e 4 C/On hlhhlhd Patented lfiec. 8, i964 tie 3,15%,1493 VARIABLE OUTHJT lUP/EPENG MEANS Claude A. (Ilarh, Houston, Tex., assigucr to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed luly '29, 1963, Set. Ne. 2%,tlltl 6 Claims. (Cl. 163-238) This invention relates to pumps and particularly to reciprocating piston pumps which are capable of delive.- ing varying volumes of iluid while the piston or pistons of the ump reciprocate at a substantially constant rate.

Other so-called variable volume pumps have been known for many years for specific uses, but for one reason or another these pumps are not well adapted for use in mobile service, such as oil and gas well or other earth well treating service, for example. Such service requires maximum utilization of available horsepower to thereby deliver the maximum volume of pumped fluid against whatever pressure may develop without exceeding the strength limits of the equipment. Such requirements necessitate minimum weight and bulk consistent with the achieving of other requirements, and ease and reliability in controlling the variable volume feature of the pump while under load. Exceptional reliability is necessary because the pump will be used often in remote areas where facilities are not available for making major repairs and because in well treating service equipment breakdown can result in great damage to the well under treatment. For example, a pump breakdown during a well cementing job could result in the cement setting up in the well casing before displacement can be elfected between the casing and well bore wall.

In conventional Well treating pumping units, a power source or prime mover, usually an internal combustion engine, transmission (which may include a torque converter) and the pump are disposed on a truck, trailer, or barge.

Any reduction in weight which can be achieved in the coupling of power to the pump of the treating unit would, obviously, permit the construction of a lighter treating unit or would permit the construction of a treating unlit having an increased pumping capacity (either in volume or pressure, or both) within allowable gross weight limitations.

Accordingly, a principal object of this invention is to provide an improved variable volume pumping apparatus which is particularly suitable for use in treating earth wells.

Another object of this invention is to provide an improved variable volume pumping apparatus which is compact in size with respect to its pumping capacity and power utilization over a wide range of pumping pressures.

A further object of this invention is to provide an improved mobile fluid pumping system for well treating service or the like.

In accordance with this invention a piston type positive displacement pump achieves an infinitely variable stroke between maximum and minimum limits through a controlled variable phase relationship between two mechanically interlocked crankshafts. These crankshafts operate through connecting rods to an equal-legged walking. beam pinned at its centerline to a plunger crosshead. Similar planetary gears are used to drive the crankshafts. A pair of multiple disc clutches, each clutch being coupled between the ring gear of one of said planetary gears and the frame of the pump, are used to establish and maintain the desired phase relationship between the crankshafts during operation. By slightly releasing one clutch to permit rotation, by a predetermined amount, of the ring shaft 55 between the bearings 63 and 65.

gear to which it is coupled, the phase of the ring gears which are coupled to each crankshaft through the planet gears is changed, thus changing the phase relationship between crankshafts and hence the piston stroke may be changed inversely with the discharge pressure to provide a hydraulic horsepower output desirably matched to the available horsepower of the prime mover.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which FIG. 1 is a simplified plan view, partly broken away and in section, of apparatus in accordance with this invention;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary end view of the drive gears of the apparatus showing chain drive coupling between the two drive gears;

FIG. 5 is a sectional view of a multiple disc clutch suitable for use in the apparatus of FIG. 1;

FIG. 6 is a sectional view taken along the line 66 of FIG. 5 and FIG. 7 is a sectional view taken along the line 7-7 of FIG. 5.

Referring to the drawing, there is shown variable volume pumping apparatus, indicated generally by the numeral lll mounted on a common frame shown only in fragments. The apparatus includes a single action reciprocating piston-type pump 12 (see FIG. 3 especially) whose piston 14 is coupled to a crosshead plunger 15, adapted to reciprocate in the guide 150, and to the center of an equal-leggedwalking beam 16 which in turn is coupled at its ends by connecting rods 18, 2t) to crankshafts 22, 24, respectively, which are journaled in bearings 17, 17a, 19, 21 and 15m, 21a, for example.

Each of the crankshafts 22, 24 has a spur gear 23 or 25 coupled coaxially thereto near the end of the crank shaft which is remote from the connecting rod 18 or 29.

The spur gears 23, 25 are coupled to spur gears 27, 29, respectively, which are fixedly coupled to and carried by the hollow shafts 31, 33, respectively. The hollow shafts 31, 33 are rigidly coupled, respectively, to flanged members 35, 37 which each extend perpendicularly with respect to the longitudinal axis of the shafts 31, 33.

Short stub shafts 39, 41 and 43, 45 extend from the flanged members 35, 37 in the same direction, their longitudinal axes being parallel to the longitudinal axis of each of the shafts 31, 33. 7

Planet gears 47, 49, seen in FIG. 2, are part of the planetary gear assembly 53 of the pair of identical planetary gear assemblies 51, 53, and are carried on the stub shafts 39, 41 and (in FIG. 2) 43, 45. The sun gears 57 shown in FIG. 2 of the planetary gear assemblies 51, 53 are each coupled to an elongated shaft 55 or 59 which extends through the hollow shafts 31, 33. The shaft 55 is journaled in suitable bearings 61, 63, 65, and 67. The shaft 59 is journaled in suitable bearings 69, '71, 73 along its length.

Each shaft 5d, 5? has a gear '75, '77 (see FIG. 4) coupled fixedly thereto, the gear 75 being coupled to the The gear '77 is coupled to the shaft 59 between the gears 71 and '73. The gears 75 and 77 are coupled together by means of a drive chain '79. A gear 81, fixedly coupled to the shaft 55 between the bearings 65 and 67, receives power from the power source 33 through the drive gear 85.

1 ring gears 57, 89 of the planetary gear assemblies 51, $3, respectively, are each coupled by means of shafts 88, 99 to the rotatable member of a multiple disc clutch assembly 91, 93, respectively. Each of the clutch assemblies has a fixed segment or part 95, 97 which is fixedly coupled to a frame element 99 of the pumping apparatus;

The previously mentioned bearings 17, 17a, 1), 19a, 21, 21a, 63, 65, d7, 71 and 73, the pump 12 and guide 15a are each secured to the frame (not shown) of the pumping apparatus, which framework also carries the power source 33. The framework referred to above is normally attached to or supported by the mobile unit, cg. a truck, which carries the apparatus.

Referring now to FIGS. 5, 6 and 7, as well as to FIG. 1, the structure of the multiple disc clutch assembly 91 (or 93), perhaps more accurately called a brake in view of its use, is shown in detail.

The outer housing and frame part 95 of the clutch assembly is fixedly secured to'the frame 99 of the pump assembly as mentioned previously. The housing and frame part 95 is divided into two functional sections. The section 1&1, adjacent to the frame section 99, has a bore 164 and piston 1% disposed around a central bar Hi3 having an outwardly extending flange 112 at its end which is remote from the frame part A piston return spring lif disposed between the outwardly extending flange E2 of the bar 1% and the piston lilo, forces the piston llilfi towards the end 114 of the section adiacent to the frame 99 except when the piston is forced forward by fluid, usually oil,'pumped into the bore 1% into which t.e piston fits. Oil is pumped into and released from the bore 16M by means of the line N5 (1537 for clutch assembly 93) which is also coupled to a clutch controller no.

The second functional part of the section 95, which extends beyond the bore iii has splines 11% on its inner wall surface and an inwardly extending flange 125) at its end which is remote from the frame section 99. A plurality of discs 1352 are fitted on and carried by the hollow splined part in the space between the piston res and the inwardly extending flange 12b.

The end of the shaft (and 9b in clutch assembly 93) has longitudinally extending splines 126 on its end part which is telescoped within the outer housing and frame part 95 from the end thereof having the inwardly The shaft 83, as previously menear 87 or 89 in extending flange T28. tioned, is rigidly coupled to the ring the case of clutch assembly $3. v

A plurality of suitably notched discs 13% are fitted over and carried by splined end of the shaft 88. The discs 122 and llfvtl are interleaved with one another, almost filling the space between the flange lit) and the forward end of the piston 1% when the piston is in its retracted position.

Each clutch assembly 91, 9.) is controlled by means of a suitable controller 1'89. example, constitute a hydraulic means for applying pressure, through lines M95 or ltllhior-both, to the respective clutch assemblies. tion when sufiicient pressure is applied to the piston (see FIG. 5) to force the clutch disc elements tightly together. By releasing part or all of the pressure, movement of the rotatable shaft 88 (or 9%) may occurwith respect to the fixed part l .(or 93) of its respective assembly.

In operation, let it be assumed that the crankshafts 2-2, 24 are initially aligned with respect to one another to provide a maximum pumping stroke of the piston- 15. Marker discs 12%, 135 are carried on the crankshafts 22, 24 in an exposed position whereby markers 13d, 136 may be seen. The markers 134, 136 are aligned in the same relative position when the crankshafts are in an in phase or maximum pump stroke position.

The markers may be painted, cut or etched into the discs 129, 135; if the checking of their relative positions The controller may, for

The clutch is in a locked posi is to be determined visually (usually using a stroboscopic light source in so doing). Alternatively, magnetic or radioactive markers may be used and their positions noted during operation of the pump by suitable dctectors which are generally well known in the art.

'As' described above, the throws of the crankshafts 22,

are connected in an iii-phase rotational relationship, and move the piston 14 of the pump 12 backwards and forward in the pump cylinder 11 at maximum stroke length as power from the gear 85 is coupled by means of the spur gear 81 to the shaft 55 and, by means of I the gears '75, 77 to the hollow shaft 66.

The rotation of the shafts 55, 59 also rotates the planet carriers 35, 37 which are used to drive the planetary gears (47, 49 in FIG. 2). The planet gears, as mentioncd previously, are carried by and are free to rotate 7 'on the shafts 39, 41 and 43, 45 which extend from the respective planet carriers.

The planet gears (47, 4-9 in FIG. 2) are also coupled to the ring gear (89 in FIG. 2) in their respective planetarygear assembly 51 or 53. The sun gears are coupled (by means of the brackets 2, 94, for example) to the shafts 88, 96, which as mentioned previously, are each coupled at one end to one of the clutch assemblies 9i, 3. The clutches are actually operated as brakes, the brake being applied to hold each shaft 33, 91; (and consequently holding the ring gears $7, as in a fixed, non-rotating position except when the phasing between the crankshafts 22, 24 is to be changed.

To change the phase relationship between the crankshafts 22, 24, the piston we in FIGS. 5 and 7) of one of the clutch assemblies 91 or b3 is retracted slightly (fluid pressure applied to the clutch assembly through the lines or 107 is reduced by means of the clutch controller 1W9) to permit some slippage of the discs 13%) whichare coupled to the shaft 38 or 90. The slippage of the discs permits rotation of the ring gear (89 in FIG. 2) of one of the planetary gear assemblies 51, 53. When the ring gear is permitted to rotate in one planetary gear assembly, the hollow shaft 31 or 33 does not rotate (or rotates less'rapidly) in the planetary gear assembly in which the ring gear rotates. Thus, the crankshafts are rotated at different rates, usually momentarily, and the phase relationship between the crankshafts is changed. The degree of slippage of the discs 130 is, under usual conditions of operation, carefully controlled. Stated difierently, the discs 130 do not become freerunning, but are maintained in frictional contact with the discs 122 while the shaft 88 or 9% is permitted to rotate.

When the stroke length of the piston M is to be changed, the clutch controller 169 is operated to partially release, momentarily, the fluid pressure on the piston 1th) of one of the clutch assemblies 91, 93 to permit slippage of one clutch by a predetermined amounnthereby changing the phase relationship between the crankshafts 22, 2:- as one ring gear (89 in FIG. 2) is rotated usually slowly) with respect to the other ring gear. Such changing of position is usually at a slow rate as compared with the rate of rotation of the crankshafts 22,24. The length of the piston stroke is at a maximum when the crankshafts 22, 24 are in phase as shown in FIG. 3 (rotating counter to one another and the markers 134, 13d are in the same relative position). Piston stroke length decreases as the crankshafts become out-of-phase with respect to each other, that is, the length of the piston stroke is at a minimum when one of the connecting rods 13, 29 is at its most forward position with respect to the piston 14 and the other connecting rod is at its most rearward position with respect to the piston 14. Since both connecting rods 18, 2b are connected to, the walking beam 16 which is coupled at itscenter to the crosshead 15, the

'movement of the piston 14 is a resultant of the, movement of the two connecting rods 18, 2% When the connecting rods are in maximum out-of-phase relationship,

the movement of the piston 14 is practically zero as to the walking beam pivots around its point of attachment to the crosshead.

When the phase relationship of the crankshafts is at an intermediate point between the iii-phase relationship and the maximum out-of-phase relationship there will be some rocking of the walking beam about its point or" attachment to the crosshead, and also some forward and backward motion of the piston 14.

The crankshafts 22, 24 may be brought into a closer in-phase relationship by rotating either one of the sun gears until the crankshafts 22, 24 are aligned to the required degree as shown by the markers 134, 136. Stated differently, if one ring gear has been rotated in relation to the other ring gear to establish an out-of-phase relationship between the crankshafts, an in-phase relationship between the crankshafts may be again accomplished by rotating the earlier moved sun gear until the crankshaft which coupled to that planetary gear assembly is again in-phase with the other crankshaft as indicated by the positions of the markers 134, 136. Alternatively, the previously unmoved ring gear may itself berotated until the two crankshafts are again aligned with one another.

The apparatus described above provides means whereby, by changing the phase relationship between the crankshafts in appropriate amounts, constant horsepower may be applied to the pump 12; even though the pressure head against which the pump works may vary over a wide range. When the pressure head is low enough to permit such operation, keeping the two crankshafts operating on an in-phase relationship results in maximum volume being displaced through the pump 12. As the pressure head increases one or" the clutches of the assemblies 91 or 93 is allowed to slip in a controlled manner to cause one of the crankshafts 22 or 24 to be moved in an increasingly out-of-phase relationship with respect to the other so that the available driving horsepower may be used to drive the piston 14 in increasingly shorter strokes and thus deliver less volume at a higher pressure.

Also, since the pump output can be continuously varied between practically no output and maximum output, there is no need for a torque converter or an additional speed varying transmission to be interposed between the power source and the pump apparatus providing the coupling between the power source 83 and the gear 81 does not cause the shafts 55, 59 to be rotated at excessive speeds.

While the apparatus has been illustrated as driving a single barrel single action reciprocating piston pump, a triplex pump, either single or double acting, or other multiple cylinder pump, such as a quintiplex pump, for example, may be coupled to suitable crankshafts which are substituted for the crankshafts 22, 24 and which are driven by the gears 23, 25.

The apparatus of the invention permits the power source to operate at a substantially constant r.p.m. rate even though the pumping rate varies widely. Thus, this apparatus is well adapted to be driven'by turbines or by an internal combustion piston-type engine operating at an optimum r.p.m. rate.

Because the pump is driven by two crankshafts, the bearing loading on the individual connecting rods is reduced. A single pump may deliver either alarge volume at moderate pressures or smaller volume at high pressures. In fixed stroke reciprocating piston-type pumps a so-called high volume pump has a relatively low maximum pumping pressure in order to prevent overloading of the connecting rod bearings or to prevent the stalling of the prime mover. Conversely, a so-called high pressure fixed stroke piston pump is limited in the volume it can pump at lower pressures because of the maximum safe r.p.m.

rate of the crankshaft even though the connecting rod bearings may not be overloaded and the horsepower capabilities of the prime mover are not exceeded.

Fumping apparatus in accordance with this invention is more versatile than conventional apparatus in that it is good both as a high pressure-low volume pump and as a low pressure-high volume pump and it admits of continuous variation of the relationship between pressure or volume driving operation. Also, because no intermediate torque converter or speed varying transmission is used, the apparatus is more compact and lighter than a conventional unit of smaller work capabilities.

The use of multiple disc clutch assemblies permits posi tive control of the phasing of the crankshafts with a mechanism which is small in size and weight yet is easily adjustable during operation.

While not mentioned previously, it should be noted that the hollow shafts 31, 33 are journaled in suitable bearings 131, 133 and 131a, 133a, respectively. The bearings are secured to the frame (not shown) of the apparatus.

What is claimed is:

l. A portable pumping unit comprising in combination a prime mover and a variable displacement pump,

said pump comprising a frame, a cylinder and piston reciprocal therein, a crosshead, means for mechanically coupling the piston to the crosshead to reciprocate the piston with reciprocation of the crosshead, a walking beam having a central part and two end parts, said walking beam being pivotally coupled to said central part of said crosshead, a pair of crankshafts, each of said crankshafts having at least one throw, a pair of connecting rods, one of said connecting rods being pivotally coupled to one end part or" said walking beam and to a throw on one of said pair of crankshafts, the other connecting rod being pivotally coupled to the other end of the walking beam and to a throw on said other crankshaft, a pair of planetary gear assemblies each comprising a sun gear, at least one planetary gear and a ring gear, said planetary gear being coupled to a rotatable planet carrier element, one of said crankshafts being operatively coupled to the planet carrier element of one of said planetary gear assemblies, the other of said pair of crankshafts being operatively coupled to the planet carrier element gear of the other of the planetary assemblies, a pair of drive shafts, means for coupling said prime mover to said drive shafts and for rotating each or" said drive shafts at least approximately at the same rate, one of said drive shafts being operatively coupled to one of said sun gears, the other of said drive shafts being operatively coupled to the other of said sun gears, a pair of multiple disc clutch assemblies each having a fixed segment and a rotatable segment, the rotatable segment of each clutch assembly being fixedly coupled to the ring gear of one of said planetary gear assemblies and the fixed segment of each clutch assembly being rigidly coupled to said frame, and means for actuating said clutch assemblies independently of one another.

2. A pumping unit in accordance with claim 1, wherein said crankshafts' are disposed parallel to one another.

3. A pumping unit in accordance with claim 1, wherein said drive shafts are disposed parallel to one another.

4. A pumping unit in accordance with claim '1, wherein said means for actuating said clutch assemblies includes a hydraulic system coupled to a piston of each clutch assembly.

5. A pumping unit in accordance with claim 1, wherein said prime mover is coupled to said drive shafts through fixed-ratio power transmitting means.

6. A pumping unit in accordance with claim 1, wherein said prime mover is a gas turbine.

No references cited. 

1. A PORTABLE PUMPING UNIT COMPRISING IN COMBINATION A PRIME MOVER AND A VARIABLE DISPLACEMENT PUMP, SAID PUMP COMPRISING A FRAME, A CYLINDER AND PISTON RECIPROCAL THEREIN, A CROSSHEAD, MEANS FOR MECHANICALLY COUPLING THE PISTON TO THE CROSSHEAD TO RECIPROCATE THE PISTON WITH RECIPROCATION OF THE CROSSHEAD, A WALKING BEAM HAVING A CENTRAL PART AND TWO END PARTS, SAID WALKING BEAM BEING PIVOTALLY COUPLED TO SAID CENTRAL PART OF SAID CROSSHEAD, A PAIR OF CRANKSHAFTS, EACH OF SAID CRANKSHAFTS HAVING AT LEAST ONE THROW, A PAIR OF CONNECTING RODS, ONE OF SAID CONNECTING RODS BEING PIVOTALLY COUPLED TO ONE END PART OF SAID WALKING BEAM AND TO A THROW ON ONE OF SAID PAIR OF CRANKSHAFTS, THE OTHER CONNECTING ROD BEING PIVOTALLY COUPLED TO THE OTHER END OF THE WALKING BEAM AND TO A THROW ON SAID OTHER CRANKSHAFT, A PAIR OF PLANETARY GEAR ASSEMBLIES EACH COMPRISING A SUN GEAR, AT LEAST ONE PLANETARY GEAR AND A RING GEAR, SAID PLANETARY GEAR BEING COUPLED TO A ROTATABLE PLANET CARRIER ELEMENT, ONE OF SAID CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE PLANET CARRIER ELEMENT OF ONE OF SAID PLANETARY GEAR ASSEMBLIES, THE OTHER OF SAID PAIR OF CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE PLANET CARRIER ELEMENT GEAR OF THE OTHER OF THE PLANETARY ASSEMBLIES, A PAIR OF DRIVE SHAFTS, MEANS FOR COUPLING SAID PRIME MOVER TO SAID DRIVE SHAFTS AND FOR ROTATING EACH OF SAID DRIVE SHAFTS AT LEAST APPROXIMATELY AT THE SAME RATE, ONE OF SAID DRIVE SHAFTS BEING OPERATIVELY COUPLED TO ONE OF SAID SUN GEARS, THE OTHER OF SAID DRIVE SHAFTS BEING OPERATIVELY COUPLED TO THE OTHER OF SAID SUN GEARS, A PAIR OF MULTIPLE DISC CLUTCH ASSEMBLIES EACH HAVING A FIXED SEGMENT AND A ROTATABLE SEGMENT, THE ROTATABLE SEGMENT OF EACH CLUTCH ASSEMBLY BEING FIXEDLY COUPLED TO THE RING GEAR OF ONE OF SAID PLANETARY GEAR ASSEMBLIES AND THE FIXED SEGMENT OF EACH CLUTCH ASSEMBLY BEING RIGIDLY COUPLED TO SAID FRAME, AND MEANS FOR ACTUATING SAID CLUTCH ASSEMBLIES INDEPENDENTLY OF ONE ANOTHER. 